1. Field of the Invention
The present invention relates generally to endoscopic forceps capable of obtaining tissue samples from a body cavity, and more particularly to endoscopic biopsy forceps with a jaw assembly capable of obtaining multiple biopsy tissue samples from a body cavity without being withdrawn from the body cavity.
2. Description of Related Art
In the diagnosis and treatment of certain illnesses, it is sometimes desirable to obtain tissue samples from deep within a body cavity, such as, for example, the large intestines of the gastrointestinal tract. In retrieving tissue samples, minimally invasive methods and devices are preferred. Endoscopic devices having dimensions which permit insertion through an endoscope, and which are capable of traversing a tortuous path through a body cavity such as the intestines, are preferred. These devices are capable of retrieving tissue samples from within a body cavity with minimal risk and/or discomfort to the patient.
An example of such a device is shown in U.S. Pat. No. 4,887,612 to Esser et al. Esser et al. disclose an elongated flexible tubular shaft with an operating handle at one end and a jaw assembly with a pair of jaws at the other end. Each jaw has a cup like end, for receiving a tissue sample, provided on the end of a jaw shank attached by a pivot to a housing, which is in turn attached to the shaft. The jaw shank of each jaw is also provided with a cam slot, in which a cam pin rides. The cam pin is connected to one end of a drive wire coaxially positioned in the tubular shaft. The other end of the drive wire is connected to the handle such that the jaw is openable and closeable in response to movement of the drive wire relative to the shaft. However, the jaw shank, pivot, pin, drive wire and jaw assembly housing structure occupy substantially all of the space immediately behind the jaw cups. Thus, the jaw assembly is only capable of receiving one tissue sample. The shaft and jaw assembly must be withdrawn from the body organ to retrieve the single sample.
In order to properly diagnose a condition or illness, it is often desirable to retrieve multiple tissue samples from a single body cavity. A device that only retrieves a single sample with each insertion must be repeatedly withdrawn and reinserted to obtain multiple samples. This is inconvenient and time consuming for the practitioner, and increases the period to which the patient is subjected to the procedure which correspondingly increases the risks associated with the procedure.
Accordingly, tissue sampling devices are desirable which are capable of retrieving multiple tissue samples from a body cavity without withdrawing the device from the body cavity.
In use, a biopsy device obtains a sample from a targeted tissue mass by closing the jaws of the device to cut or tear a tissue sample from a targeted mass. Examples of targeted tissue mass include a cavity wall, a polyp, etc. Ideally, the relative position of the jaw assembly of a biopsy device should remain fixed with respect to the tissue being sampled, so that the tissue sample size, source and quality can be selectively controlled. Thus, it is preferable to have a device that permits the jaw assembly to remain stationary relative to the targeted tissue, or a device which avoids moving the targeted tissue relative to the jaw assembly during the actual taking of the tissue sample. To achieve this end, it is desirable in the design of tissue sampling devices to provide that portion of the device which is inserted into the cavity, i.e., the distal end, with as few externally exposed moving parts as possible, particularly jaw assembly parts close to the distal end of the jaw assembly. The externally exposed parts referred to are those parts, other than the jaws, which are exposed externally of the device such that the parts could contact and move the targeted tissue or tissue immediately adjacent to targeted tissue during the taking of a tissue sample. The movement referred to is movement of jaw assembly elements relative to the device shaft, relative to the distal end of the jaw assembly, or relative to the tissue being sampled. By eliminating externally exposed moving parts, undesired tissue movement can be avoided. Examples of externally exposed moving parts include, but are not limited to, the tubular shaft of an endoscopic device if it moves axially or radially relative to the jaws, as for example in a device in which the jaw assembly is stationary relative to an inner drive wire, and the outer tubular shaft is movable relative to the inner wire to, for example, open and close the jaws. Further examples of externally exposed moving parts include, but are not limited to, jaw assembly parts such as housing members or jaw actuating members, sleeves or arms. These types of moving parts are known to contact and transmit movement either directly to targeted tissue, or indirectly to targeted tissue by contacting tissue adjacent to targeted tissue, thus reducing the accuracy of the sampling procedure as well as the quantity and quality of the tissue samples retrieved.
A device capable of retrieving multiple tissue samples is disclosed in U.S. Pat. No. 5,318,589 to Lichtman. Lichtman discloses jaws mounted on an inner member, a movable intermediate member extendable over the jaws to close the jaws, and an outer sleeve which occupies substantially the entire length of the intermediate shaft. The inner member and outer sleeve are stationary relative to the jaws. The outer sleeve prevents movements of the intermediate shaft from being transmitted to the targeted or surrounding tissue. The arrangement taught by Lichtman has the disadvantage of requiring a third coaxial member, i.e., the stationary inner member, which occupies space in the jaw assembly that could otherwise be occupied by tissue samples, thus limiting the number of samples that can be retrieved without withdrawing the distal end from the body cavity.
U.S. Pat. No. 5,542,432 to Slater et al. discloses a biopsy forceps device capable of retrieving multiple tissue samples. The device has a pair of jaw cups, each on a thin resilient arm connected to an elongate tubular shaft such that they are axially stationary relative to the tubular shaft, i.e. stationary relative to the targeted tissue. A cylinder connected to an inner control wire extends over the resilient arms to close the jaws. Each additional tissue sample taken pushes the previous sample further back into the jaw assembly, between the thin resilient arms. The disadvantage of this arrangement is that the cylinder may be externally exposed to contact and transmit movement to targeted tissue, thus affecting the quality and quantity of samples retrieved. The arrangement has an additional disadvantage in that the thin resilient arms lack means to laterally contain collected samples, thus tissue samples are likely to be lost to retrieval by being pushed or jarred from the storage area between the thin resilient arms. Finally, this arrangement suffers yet another disadvantage in that the thin resilient arms permit the jaws to move laterally out of alignment with each other, such that the quality and/or quantity of a tissue sample may be diminished.
There is therefore a need for an endoscopic biopsy device capable of taking multiple biopsy samples without being withdrawn from a body cavity, the device having a jaw assembly with few or no externally exposed moving parts (except the jaws) and having a relatively large and contained storage area for collecting multiple samples.